This invention relates to soluble, film-forming polyamides, polyimides and polyamide-imides and their copolymers made using 3,5-diamino-t-butylbenzene, and, more particularly, to partially soluble, high Tg, high thermal stability, lower density, lower-moisture-uptake polyamides, polyimides and polyamide-imides and their copolymers made using 3,5-diamino-t-butylbenzene.
Aromatic polyamides, polyimides and polyamide-imides have found extensive use in industry as fibers, composites, molded parts and dielectrics due to their toughness, flexibility, mechanical strength and high thermal stability, and, in the case of polyimides, their lower dielectric constant and high electrical resistivity. Such polymers have been used in both film and coating form as advanced materials for such uses as passivation and insulating coatings, interlevel dielectrics, die attach adhesives, flexible circuit substrates, and the like.
Although current polyamides, polyimides, and polyamide-imides made from, for instance, metaphenylenediamine have the toughness, flexibility and thermal stability necessary to meet the rigorous processing and operating conditions required for certain uses, they do not exhibit the low dielectric constant and reduced moisture uptake shown by lower thermal stability polymers such as polyethylene and polytetrafluoroethylene. The latter polymers, however, are not useful despite their excellent dielectric and moisture uptake properties if thermal stability requirements are demanding. In addition, polyamides, polyamide-imides and particularly polyimides are generally insoluble even in solvents like N-methyl pyrrolidone (NMP) or dimethyl acetamide (DMAC) which inhibits their usefulness in important areas.
Now it has been found that improved polymers exhibiting the combination of low dielectric constant, lower moisture uptake, partial solubility in N-methylpyrrolidone, lower density, and thermal stability can be found among the polyamides, polyimides, and polyamide-imides and their copolymers made from 3,5-diamino-t-butylbenzene.